WO2011020211A1

WO2011020211A1 - Random access method and base station, relay node and system utilizing the method

Info

Publication number: WO2011020211A1
Application number: PCT/CN2009/000939
Authority: WO
Inventors: 杨涛
Original assignee: 上海贝尔股份有限公司; 阿尔卡特朗讯
Priority date: 2009-08-17
Filing date: 2009-08-17
Publication date: 2011-02-24
Also published as: CN102474878A; CN102474878B

Abstract

A random access method utilized in a wireless communication system is provided by the present invention, the wireless communication system comprises a base station, a user equipment and at least one relay node, the user equipment is located within the service area of the base station and/or at least one relay node, the random access method comprises following steps: based on the Packet Random Access CHannel (PRACH) message detection report, which is sent by at least one relay node and regarded as a detection result of the PRACH message sent from the user equipment, the base station selects a relay node to serve the user equipment, and sends the selection result to the selected relay node; based on detecting the PRACH message sent from the user equipment by the base station itself and/or the PRACH message detection report, which is sent by the selected relay node and regarded as a detection result of the PRACH message sent from the user equipment, the base station computes the timing advance message, and feeds back the timing advance message to the user equipment and/or the selected relay node; the user equipment sends the uplink data based on the received timing advance message. A base station and relay node for implementing the random access method, a wireless communication system comprising such base station and relay node are also provided by the present invention. According to the random access method of the present invention, the present invention is able to support the existing user equipments and realize the random access in a system with relay nodes disposed.

Description

Random access method and base station, relay node and system using the same

Technical field

The present invention relates to a random access procedure in an LTE-A system, and more particularly to a random access procedure in a scenario in which a Type II relay is deployed. Background technique

Currently, most of the LTE Releases standards (including basic technologies, functions, features, etc.) have been basically completed, and LTE-Advanced has entered the preparation phase. LTE-A is a smooth evolution based on LTE. Based on such a positioning, the LTE-Advanced system should naturally support all the functions of the original LTE and support forward and backward compatibility with LTE, that is, the terminal of R8 LTE can access the future. The LTE-Advanced system, the LTE-Advanced terminal can also access the R8 LTE system.

In the random access procedure of LTE, the user terminal transmits a packet random access channel (PRACH) message and waits for a response message from the serving base station in a fixed time window. If no response message is received in this time window, the user terminal considers that the previous PRACH transmission failed and is ready to retransmit the PRACH message. (See 3GPP TS 25.321 and 3GPP TS 25.303). The response message fed back by the serving base station includes: TC-RNTI, RAID, UL Grant, and TA (time advance), etc., where TC-RNT indicates Temporary Cellular - Radio Network Temporary Identity and RAID indicates random access code Identification, UL Grant indicates an uplink resource allocation command, and TA indicates Timing Advance information. Since the distance of the user equipment from the serving base station is variable, the propagation delay is also variable. In order to ensure that the serving base station can accurately receive the data of the user equipment, an adaptive frame adjustment technique is adopted. Once the user equipment is registered through the access channel, the serving base station tests the propagation delay and sends a timing advance instruction to the user equipment, and the user equipment performs adaptive frame adjustment according to the instruction, so that the user equipment sends data to the serving base station at the time and the base station. The received time slots are identical, that is, uplink synchronization is established. The TA value is calculated by the serving base station based on the propagation delay amount and notified to the user equipment. The amount of propagation delay can be determined based on the received power of the message, the time at which the message is received, and the like.

As two core technologies for LTE-Advanced airspace expansion, Relay (Relay) and CoMP (Coordinated Multicast) technologies have made great innovations in the LTE standard.

Relay technology is based on the original site, by adding some new Relay stations (or relay nodes), increasing the distribution density of stations and antennas. These new relay nodes and primary base stations (DeNB (donor) The eNB)) is connected via wireless, and there is no wired connection between the transmission network and the downlink data. The downlink data is first transmitted to the primary base station and then to the relay node, and the relay node is transmitted to the terminal user, and the uplink is reversed. This method narrows the distance between the antenna and the end user, and can improve the link quality of the terminal, thereby improving the spectrum efficiency and user data rate of the system.

Two types of relays, Type I Relay and Type II Relay, are currently proposed. The application scenario of type I relay is mainly to increase the coverage area and blind spot coverage. It has independent PCI, has pilot channel and synchronization channel, and broadcasts its own system information, which is equivalent to an independent base station, but it has a problem. Interference problem between the relay node (relay node) and the DeNB. Therefore, the type II relay is required. The application scenario of the type II relay is to increase the cell capacity and the extended coverage area. The PCI is the same as the DeNB, and is mainly controlled by the DeNB, and is mainly used for coordinated transmission. The Type II trunk belongs to the L2 relay and does not have an independent cell ID, and therefore does not create a cell. The DeNB has no interference problem and can work together on the user equipment. In the Type II relay application scenario, an associated signaling connection is established between the terminal and the base station, and in the Type I relay scenario, a signaling connection is established between the terminal and the relay node.

Currently, two possible Type II relay operations are proposed to increase cell capacity:

1. Collaborative transmission;

2. Non-cooperative transmission. The destination receives the transmission only from the relay node, which is called the post-decoding forwarding scheme. This is a typical relay node operation in which the relay node forwards data received from the source to the destination in a time division multiplexed TDM manner.

For coverage area extension applications, trunks can only work in non-cooperative transmission mode. Table 1 summarizes the possible types of II relay operating modes. Table 1: Type II Relay Application

The difference between Cases 1, 2 and Case 3 is that for Cases 1, 2, the user equipment is still within the coverage of the DeNB.

In order to design a random access procedure for a scenario in which a Type II relay is deployed, the following points need to be considered: 1. For a Type II relay operation scenario, the user equipment must establish an RRC connection with the DeNB, because Type II The cell is not created. 2. For Case 1, the user equipment must synchronize with both the DeNB and the relay node on the uplink. For Case 2 and Case 3, the user equipment only needs to synchronize with the serving relay node on the uplink.

3. It should not affect the operation of existing user equipment.

Because the access procedure defined by LTE does not consider relay operations, it cannot be directly applied to scenarios of relay operations. The access procedure of the Type II relay operation scenario has not been involved in the LTE-advanced standard.

The present invention defines a feasible method for a random access procedure associated with Type II relays under the above conditions. Summary of the invention

The object of the present invention is to propose a random access procedure in a scenario in which a Type II relay node is deployed, which can support existing user equipment.

According to a first aspect of the present invention, a random access method for use in a wireless communication system is provided. The wireless communication system includes a base station, a user equipment, and at least one relay node, and the user equipment is located at the base station. Within the scope and/or within the service range of the at least one relay node, the random access method includes the following steps: the base station is based on being sent by the at least one relay node as the user equipment a PRACH message detection report of the detected result of the transmitted PRACH message, selecting a relay node for serving the user equipment, and transmitting a selection result to the selected relay node; the base station transmitting the user equipment according to itself Detection of the PRACH message and/or a PRACH message detection report sent by the selected relay node as a result of detecting the PRACH message sent by the user equipment, calculating a timing advance message, and reporting to the user equipment And/or the selected relay node feedback time advance message; and the user equipment based on the received time Inter-advance message, sending uplink data.

Preferably, when the base station detects the PRACH message sent by the user equipment but has not received the PRACH message detection report of the at least one relay node, the random access method further includes the following steps: And generating, according to the detection of the PRACH message sent by the user equipment, a temporary time advance message, and transmitting the message to the user equipment; and the user equipment sending the uplink data based on the temporary time advance message.

Preferably, the random access method further includes the following steps: the selected relay node forwards the received timing advance from the base station to the user equipment when receiving the timing advance message from the base station Message. Preferably, before the user equipment and the selected relay node receive the timing advance message from the base station, the random access method further includes the following steps: the at least one relay node is based on its own Determining a PRACH message sent by the user equipment, generating a temporary time advance message, and transmitting the message to the user equipment; and selecting, by the user equipment, one of the received temporary time advance message, based on the selected temporary Time advance message, sending uplink data.

Preferably, the random access method further comprises the step of: the base station notifying the PRACH related configuration to all the relay nodes.

Preferably, the wireless communication system is an LTE-A system.

Preferably, the at least one relay node is a type II relay node.

According to a second aspect of the present invention, a base station is provided, including: a receiving unit, configured to detect a PRACH message from a user equipment, and receive a PRACH message sent by the at least one relay node as sent by the user equipment. a PRACH message detection report of the detection result, a selecting unit, configured to detect a report based on the PRACH message, and select a relay node for serving the user equipment; and the processing unit is based on the PRACH message sent by the user equipment by itself Detecting and/or a PRACH message detection report sent by the selected relay node as a result of detecting the PRACH message sent by the user equipment, calculating a timing advance message; and transmitting unit for selecting the selected The relay node transmits a selection result of the selection unit and is used to feed back a timing advance message to the user equipment and/or the selected relay node.

Preferably, when the receiving unit detects the PRACH message sent by the user equipment but has not received the PRACH message detection report of the at least one relay node: the processing unit sends the user equipment according to the user equipment The detection of the PRACH message generates a temporary time advance message, and the transmitting unit sends a temporary time advance message to the user equipment.

According to a third aspect of the present invention, a relay node is provided, including: a receiving unit, configured to detect a PRACH message from a user equipment; and a processing unit, configured to generate a PRACH message detection report based on the detected PRACH message; And a sending unit, configured to send the generated PRACH message detection report to the base station.

Preferably, the processing unit further generates a temporary timing advance message based on the detection of the PRACH message sent by the user equipment by itself; the sending unit sends a temporary time advance message to the user equipment; The unit receives a timing advance message from the base station; and the transmitting unit transmits the received timing advance message from the base station to the user equipment. Preferably, the relay node is a type II relay node.

According to a fourth aspect of the present invention, a wireless communication system is provided, comprising the above base station, user equipment, and at least one of the above relay nodes.

Preferably, the wireless communication system is an LTE-A system. DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from

1 is a schematic structural diagram of a base station and a relay node in a wireless communication system according to the present invention; FIG. 2 is a schematic structural diagram of a communication system according to a first embodiment of the present invention;

3 shows a signal flow diagram of a random access procedure according to a first example of the first embodiment of the present invention; FIG. 4 shows a signal flow of a random access procedure according to a second example of the first embodiment of the present invention. Figure 5 is a block diagram showing the structure of a communication system in accordance with a second embodiment of the present invention;

6 is a block diagram showing the structure of a communication system according to a third embodiment of the present invention;

7 is a signal flow diagram showing a random access procedure of a first example according to a third embodiment of the present invention;

Fig. 8 is a signal flow diagram showing a random access procedure of a second example according to the third embodiment of the present invention. Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, some specific embodiments are for illustrative purposes only and are not to be construed as limiting the invention in any way. It is to be noted that the illustrations are only illustrative of the differences from the prior art, and the conventional structures or structures are omitted so as not to obscure the understanding of the present invention.

The main concept of the random access procedure proposed by the present invention is: when detecting the PRACH message of the user equipment, the relay node sends a PRACH message detection report to the DeNB, including the PRACH message detection power, time information, etc.; the DeNB selects the service user equipment. The relay node regenerates the timing advance (TA) based on the selected relay node's report and its own time information, and notifies the user equipment of the regenerated TA. On the user equipment side, instead of the temporary TA, the newly received TA is used for uplink data transmission.

A wireless communication system according to an embodiment of the present invention includes a base station, a user equipment, and at least one relay section Point, the user equipment is located within the service area of the base station and/or is located within the service range of the at least one relay node. FIG. 1 is a block diagram showing the structure of a base station and a relay node in a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 1, the base station 100 includes a transmitting unit 101, a receiving unit 102, a processing unit 103, and a selecting unit 104. The relay node 200 includes a receiving unit 201, a transmitting unit 202, and a processing unit 203.

Of course, the base station 100 and the relay node 200 further include, for example, a control unit that performs control, a storage unit that performs storage, and the like, and only parts related to the present invention are shown here to avoid making the description of the present invention unclear.

After the user equipment sends the PRACH message, the receiving unit 101 of the base station 100 and the receiving unit 201 of the relay node 200 both perform the detection of the PRACH message. When the receiving unit 201 detects the PRACH message, the processing unit 203 of the relay node 200 processes the detection result of the PRACH message, and generates a PRACH message detection report, and then the sending unit 202 sends the generated PRACH message detection report to the base station. 100.

The processing unit 103 of the base station 100 processes the PRACH message detection report sent by the relay node, and the selection unit 104 selects a relay node for serving the user equipment based on the processing result of the processing unit 103, and the selected unit is selected by the transmitting unit 101. The relay node sends the selection result.

The processing unit 103 of the base station 100 also calculates a timing advance message based on its own detection of the PRACH message transmitted by the user equipment and/or a PRACH message detection report from the selected relay node, and is transmitted by the transmitting unit 101. The user equipment and/or the selected relay node feeds back a timing advance message.

The processing unit 103 of the base station 100, when detecting the PRACH message sent by the user equipment but has not received the PRACH message detection report of the relay node, generates a temporary based on the detection of the PRACH message sent by the user equipment by itself. The time advance message is sent by the transmitting unit 101 to the user equipment.

The processing unit 203 of the relay node 200 also generates a temporary timing advance message based on its own detection of the PRACH message transmitted by the user equipment, and transmits it to the user equipment by the transmitting unit 202. Further, when the receiving unit 201 receives the timing advance message from the base station, the relay node 200 transmits the received timing advance message from the base station to the user equipment by the transmitting unit 202. The random access procedure in the above three cases of the Type II relay operation will be described in detail below. Case 1:

Fig. 2 is a block diagram showing the structure of a communication system in accordance with a first embodiment of the present invention.

For this case, type Π relay is used to increase the cell capacity, and Type II relay works in a cooperative transmission with the DeNB. That is to say, the user equipment directly performs data transmission with the DeNB, and also relays data transmission between the user equipment and the DeNB through the serving relay node.

In this case, the user equipment is within the coverage of the DeNB and needs to establish uplink synchronization with both the serving relay node and the DeNB.

FIG. 3 shows a signal flow diagram of a random access procedure according to a first example of the first embodiment of the present invention. In step S101, the DeNB notifies the PRACH related configuration to all deployed Type II relays so that each relay node knows when and where to detect the PRACH message from the user equipment. Assume that there are Type II Relay Node 1 and Type II Relay Node 2 deployed.

In step S102, the user equipment performs a conventional PRACH transmission that has been defined by LTE, and waits for a PRACH Response (PR) message in a predefined window.

The DeNB and each relay node detect a PRACH message.

In step S103, the DeNB operates according to the operation defined by LTE, including TC-RNTI allocation, temporary TA calculation, resource allocation, and the like. The temporary TA is calculated based on the amount of propagation delay when the DeNB receives the PRACH message, that is, the received power of the message, the time of receiving the message, and the like.

In step S104, the DeNB feeds back a PRACH response message (containing a temporary TA) so that the user equipment can receive the message in its predefined window.

In step S106, the user equipment transmits data based on the TA in the received PRACH response message, and establishes temporary uplink synchronization with the DeNB. Thereafter, the user equipment can perform data transmission with the DeNB.

At the same time, after detecting the PRACH message, each relay node sends a PRACH message detection report, such as PRACH message reception power, reception time information, etc., to the DeNB after detecting the PRACH message (S105).

The DeNB then selects a relay node for serving the user equipment in step S107, and recalculates the TA according to the report of the selected relay node, so that the user equipment simultaneously transmits the uplink data based on the new TA with the DeNB and the The selected relay node is synchronized.

In step S108, the DeNB transmits a new TA to the user equipment in the MAC layer signaling, and notifies the selected relay node of its selection result (S109).

In step S110, the user equipment performs subsequent uplink transmission based on the newly received TA information. Lose. At this point, the user equipment is able to establish uplink synchronization with both the eNB and the selected relay node. Thereafter, the selected relay node detects the uplink transmission of the user equipment and performs retransmission in a manner of cooperating with the DeNB for transmission.

In this embodiment, uplink synchronization of the user equipment with the DeNB and the selected relay node is established through the above steps. In addition, existing user equipment operations are not affected.

4 is a signal flow diagram showing a random access procedure of a second example according to the first embodiment of the present invention. In the random access procedure according to the first example of the first embodiment of the present invention, if step S107 can end during the configured PRACH response message transmission window, and the TA in the PRACH response message has considered the selected relay The time information reported by the node, the user equipment can establish uplink synchronization with the DeNB and the relay node after receiving the PRACH response message, so there is no need to retransmit the TA, ie, steps S108 (and S103) are not required. A signal flow diagram of the random access procedure according to the second example of the first embodiment of the present invention is as shown in FIG. Situation 2

Fig. 5 is a block diagram showing the structure of a communication system in accordance with a second embodiment of the present invention.

For this case, type Π relay is used to increase the cell capacity, and the Type II relay operates in a manner of non-cooperative transmission with the DeNB, and the data transmission between the user equipment and the DeNB is relayed through the relay node.

For this case, a method similar to the case 1 can be employed. The only difference is that since the type II relay node and the DeNB do not cooperate in transmission, the user equipment does not need to synchronize with the DeNB, and only needs to implement uplink synchronization with the relay node.

Therefore, for this case, the random access procedure is the same as the random access procedure of the first example and the second example according to the first embodiment of the present invention, except that in step S107, the DeNB is based only on the selected relay node. Report to calculate the new TA command so that the user device only needs to synchronize with the selected relay node. In addition, existing user equipment operations are not affected.

In this case, uplink synchronization of the user equipment with the selected relay node is implemented, and the capacity of the DeNB cell can be improved by using the relay node. Moreover, the random access procedure has no effect on user equipment operations conforming to the existing LTE standard, and thus supports backward compatibility. Youth condition 3 Fig. 6 is a block diagram showing the structure of a communication system in accordance with a third embodiment of the present invention.

For case 3, use Type II trunking to extend the coverage area. Therefore, the user equipment must relay the data transmission between the user equipment and the DeNB through the relay node outside the coverage of the DeNB, and thus the relay node operates in a non-cooperative transmission manner with the DeNB.

The deployed relay node first detects the PRACH message of the user equipment. There are two options depending on the PRACH response message transmission scheme:

Option 1: DeNB is responsible for generating PRACH response messages

FIG. 7 shows a signal flow diagram of a random access procedure of a first example according to a third embodiment of the present invention. In the random access procedure of the first example according to the third embodiment of the present invention, as in the first embodiment and the second embodiment described above, it is assumed that the type II relay node 1 and the type II relay node 2 are deployed.

In step S201, the DeNB notifies the PRACH related configuration to all deployed Type II relays so that each relay node knows when and where to detect the PRACH message from the user equipment.

At step S202, the user equipment performs a conventional PRACH transmission that has been defined by LTE and waits for a PRACH Response (PR) message in a predefined window.

In step S205, the deployed relay node 1, 2 first detects the PRACH message and sends a PRACH message detection report to the DeNB, including PRACH message detection power, reception time information, and the like. The DeNB then selects a relay node serving the user equipment according to a predefined rule, calculates a TA based on the report of the selected relay node, and feeds back a PRACH response message to the selected relay node, including the allocated TC-RNTI and corresponding TA information. Then, the selected relay node sends a PRACH response message to the user equipment, including the allocated TC-RNTI, the allocated resource, the TA, and the like. After that, the user equipment establishes uplink synchronization with the selected relay node.

In the first example according to the third embodiment of the present invention, the transmission of the PRACH response message may be delayed due to communication between the DeNB and the relay node, so that the user equipment cannot receive the PRACH response message in its predefined window, so Impact on existing LTE user equipment operations.

Option 2: The relay node is responsible for generating the PRACH response message

FIG. 8 shows a signal flow diagram of a random access procedure according to a second example of the third embodiment of the present invention. In order to solve the influence on the operation of the existing user equipment due to the lag of the PRACH response message transmission in the random access procedure according to the first example of the third embodiment of the present invention, in the second example according to the third embodiment of the present invention During the random access procedure, the relay node sends a PRACH response message immediately after detecting the PRACH message. In order to implement the random access procedure, it is assumed that the TC-RNTI is also used by the relay node. Assignment is not assigned by the DeNB. This process is shown in Figure 8, which is described in detail below.

In the same manner as the first example according to the third embodiment of the present invention, in step S301, the DeNB notifies the PRACH related configuration to all deployed Type II relays, so that each relay node knows when and where to detect from the user equipment. PRACH message.

At step S302, the user equipment performs a conventional PRACH transmission that has been defined by LTE and waits for a PRACH Response (PR) message in a predefined window.

In step S303, the relay node detects the PARCH message. The relay node that satisfies the predefined rule generates a PRACH response message, and the step includes allocating a TC-RNTI, allocating resources and calculating a TA as the DeNB. At step S304, the PRACH response message is sent to the user equipment such that the user equipment can receive the message in its predefined window.

On the user equipment side, if more than one PRACH response message is received, the user equipment selects one of them in step S306, and establishes uplink synchronization with the corresponding relay node based on the selected PRACH response message (for example, relaying) Node 1) (step S308). Since only the relay node 1 selected by the user equipment can correctly receive data from the user equipment, the selected relay node 1 forwards the data to the DeNB.

In addition, after detecting the PRACH message, the relay node sends its PRACH detection information report to the DeNB, including the allocated TC-RNTI, the allocated resources, and the like, in step S305. DeNB is then selected (e.g. relay node 2) (step S307) that selects a notification 2 (step S309) _o DeNB will relay node to relay node to a user equipment according to predetermined criteria, the relay node 2 and then to The user equipment transmits a new TA (step S310) so that the user equipment can establish uplink synchronization with the relay node 2 for future data transmission.

After that, all transmissions between the user equipment and the DeNB pass through the relay node 2.

An advantage of the random access procedure according to the second example of the third embodiment of the present invention is that the existing user equipment operation is not affected since the PRACH response message transmission does not lag.

However, its disadvantages are: There may be more than one PRACH response message to be transmitted on the DL Uu interface. Another problem is that the TC-RNTI is allocated by the relay node instead of by the DeNB. However, this can be easily implemented. For example, the DeNB can allocate a TC-RNTI pool to each relay node in the configuration phase, so that the relay node can only allocate the TC-RNTI in its pool to the user equipment in its coverage area. The DeNB can allocate other TC-RNTIs to the user equipments it directly serves. Further, in the random access procedure according to the second example of the third embodiment of the present invention, the relay node should be able to respond in the PRACH The temporary TA is calculated before the transmission. The embodiments described above are for illustrative purposes only and are not intended to limit the scope of the invention. It will be apparent to those skilled in the art that various modifications and changes in the form and details may be made without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents.

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Claims

Rights request

What is claimed is: 1. A random access method for use in a wireless communication system, the wireless communication system comprising a base station, a user equipment, and at least one relay node, the user equipment being located within a service range of the base station and/or located at Within the service scope of the at least one relay node, the random access method includes the following steps:

Determining, by the base station, a PRACH message detection report sent by the at least one relay node as a result of detecting a PRACH message sent by the user equipment, selecting a relay node for serving the user equipment, and The selected relay node sends the selection result;

The base station detects, according to its own detection of the PRACH message sent by the user equipment, and/or a PRACH message detection report sent by the selected relay node as a result of detecting the PRACH message sent by the user equipment, Calculating a timing advance message and feeding back a timing advance message to the user equipment and/or the selected relay node;

The user equipment transmits uplink data based on the received timing advance message.

The random access method according to claim 1, when the base station detects a PRACH message sent by the user equipment but has not received a PRACH message detection report of the at least one relay node, the random access method The access method also includes the following steps:

The base station generates a temporary time advance message based on the detection of the PRACH message sent by the user equipment by itself, and sends the temporary time advance message to the user equipment;

The user equipment transmits uplink data based on the temporary time advance message.

3. The random access method according to claim 1, further comprising the steps of:

The selected relay node forwards the received timing advance message from the base station to the user equipment upon receiving the timing advance message from the base station.

The random access method according to claim 3, before the user equipment and the selected relay node receive the timing advance message from the base station, the random access method further includes the following steps:

The at least one relay node generates a temporary time advance message based on the detection of the PRACH message sent by the user equipment, and sends the temporary time advance message to the user equipment;

The user equipment selects one of the received temporary time advance messages, and transmits uplink data based on the selected temporary time advance message.

5. The random access method of claim 1, further comprising the step of: base station to all relay sections Point to notify PRACH about the configuration.

The random access method according to claim 1, wherein the wireless communication system is an LTE-A system.

The random access method according to claim 6, wherein the at least one relay node is a type II relay node.

8. A base station comprising:

a receiving unit, configured to detect a PRACH message from the user equipment, and receive a PRACH message detection report sent by the at least one relay node as a detection result of the PRACH message sent by the user equipment,

a selecting unit, configured to select, according to a PRACH message detection report, a relay node used to serve the user equipment;

a processing unit, based on the detection of the PRACH message sent by the user equipment by itself and/or the PRACH message detection report sent by the selected relay node as a detection result of the PRACH message sent by the user equipment, Calculate the timing advance message;

And a sending unit, configured to send a selection result of the selecting unit to the selected relay node, and to feed back a timing advance message to the user equipment and/or the selected relay node.

9. The base station according to claim 8, when the receiving unit detects a PRACH message sent by the user equipment but has not received the PRACH message detection report of the at least one relay node,

The processing unit generates a temporary time advance message based on the detection of the PRACH message sent by the user equipment by itself, and

The sending unit sends a temporary time advance message to the user equipment.

10. A relay node, comprising:

a receiving unit, configured to detect a PRACH message from the user equipment;

a processing unit, configured to generate a PRACH message detection report based on the detected PRACH message;

And a sending unit, configured to send the generated PRACH message detection report to the base station.

The relay node according to claim 10, wherein

The processing unit further generates a temporary timing advance message based on the detection of the PRACH message sent by the user equipment by itself; Transmitting unit sends a temporary time advance message to the user equipment; the receiving unit receives a time advance message from the base station;

The transmitting unit transmits the received timing advance message from the base station to the user equipment.

The relay node according to claim 10 or 11, wherein the relay node is a type II relay node.

A wireless communication system comprising a base station according to claim 8 or 9, a user equipment and at least one relay node according to one of claims 10-12.

14. The wireless communication system according to claim 13, wherein the wireless communication system is an LTE-A system.